Electrical jack type connectors are used in a wide variety of industries, including the telecommunications industry, for interfacing with plugs on ends of cords and wires used to interconnect various system components. Modular jacks are one of the most common types of electrical jacks because of their compact and lightweight design configuration that enables them to be readily and easily incorporated into the body and electrically connected to the system of many different component applications and configurations, including those of relatively small size.
In a typical modular jack, a housing body defines a socket shaped to receive in a quick connect/disconnect fashion a complementary shaped, industry standard modular plug. To form an electrical connection with the plug, modular jacks commonly include a number of side-by-side wire contacts that extend across the socket. The number of wire contacts varies depending on the application of use and can be as many as ten. The plug includes plug contacts that engage the necessary number of wire contacts as the plug is inserted and locked in the socket.
The wire contacts in a typical modular jack are designed to bias across the socket and into engagement with the plug contacts to provide a reliable electrical connection. Each wire contact typically includes a tail portion fixed relative to the housing and electrically connected to the circuitry of the particular component, an opposite free end portion and an intermediate contact portion that extends across the socket between the fixed and free end portions for contact with the plug contacts. The intermediate contact portion and the free end portion of the wire contact are shifted against the natural bias of the wire contact from a non-engaged position to an engaged position upon plug insertion.
In many situations, it is common that the circuitry of a particular system requires certain of the plug contacts to be selectively shorted with one another. For example, in modular jacks with eight wire contacts, there are instances in which the operating circuitry of the component requires shorting of as many as four of the non-engaged wire contacts. It is important that the shorting connections be reliable and capable of withstanding relatively heavy use. Specifications are known to require modular jacks to withstand 500 to 750 cycles of plug insertion and removal.
However, modular jacks have been found to produce undesirable intermittent electrical contact caused, in significant part, by ineffective shorting designs. For instance, one known shorting design employs cross-over wires interconnecting the free end portion of the wire contacts identified for shorting. More specifically, in typical modular jacks, each of the free end portions of the wire contacts extend through a slot at the rear of the housing. The slots each have a bottom end portion and an open end portion and are defined by a number of side-by-side thin fins. The slots insulate the wire contacts against contact with one another and guide the deflection caused by the plug being inserted into the socket. With this jack design, the end portions of the cross-over wires are bent and tucked generally into the slots containing the free end portions for the wire contacts preselected for shorting. Upon plug insertion, the non-engaged contacts remain biased against the end portions of the cross-over wires.
The thin slot forming fins are known to deflect and allow misalignment between the end portions of the cross-over wires and the free end portions of the wire contacts in the slot. Typically, both the wire contacts and the cross-over wires have a circular cross-section which increases the potential for the wires at the shorting connection to shift against one another and become misaligned. It also is known that the end portions of the cross-over wires are not adequately tucked into or otherwise positioned in the slots, such as in the slot bottom portion, and as a result, the fins tend to deflect and allow misalignment. Fin deflection increases the potential for interference with the shifting of adjacent wire contacts that are necessary for engagement with plug contacts. As a result, jacks with this type of shorting design tend to produce undesirable intermittent electrical connections and fail reliability standards.
Another known designs employs a printed circuit board type assembly mounted to the rear of a jack of the type described above. The board includes a number of grooves in alignment with and adjacent to the slot bottoms containing the biased wire contacts designated for shorting. Each groove is lined with an electrical conductive material, such as gold foil, and is positioned with respect to its particular slot such that the wire contacts designated for shorting bias into electrical contact with the respective foil lined groove. The board includes an electrical path masked between the grooves to provide the shorting interconnection. An undesirable shortcoming of this design is the intermittent electrical connections known to occur at the shorting connections due to the conductive material flaking and pulling loose from the grooves. This is especially a concern in situations with even modest cycling requirements.
Thus, there is a need for a more reliable shorting assembly for electrical contacts of jacks and the like that reduces potential for intermittent shorting connections and withstands relatively heavy use.